Protective and performance enhancing helmets, goggles, and other such eye-shielding devices often provide protection for a wearer's eyes while maintaining or enhancing optical functionality for the wearer, for example, by magnifying, clarifying, darkening, tinting, or lightening (“bleaching”) light transmission through a viewing lens of the device. To facilitate a desired optical performance, a viewing lens may be adapted to minimize, avoid, or compensate for a variety of conditions, including, for example, fog, condensation, sun glare, or darkness. One optical property sought by wearers of eye-shielding devices is the ability to absorb or reduce the amount of sunlight and/or glare in bright conditions. It is desirable that such light absorption be fast and reversible (so that the eye-shielding devoice returns to a “clear state” in the absence of bright light). Under certain conditions, the wearer should be able to control the amount of light-absorption or the tint of such a device. In other instances, an automatic response to light is required. It is also desirable to provide such a device in an “after market” kit which can be easily applied to any eye-shielding device. In some instances, it is advantageous to make such devices “removable” by the end-user.
In the past, “darkening” or “self-tinting” eye-protection devices have had a number of shortcomings. For example, some attempts have been made to integrate such devices into the viewing lens of an eye-shielding device, such as for example motorcycle helmets. However, such devices are typically an integral part of the visor of the helmet and have to be purchased and used with a particular helmet. Moreover, such devices are not separable or removable from the visor of the helmet.
Speed is also a factor. Many devices, for example photochromic devices, are slow to react to a change in light conditions. In addition, a user has no control over the color or amount of tint or light absorption of such a device, including the ability to “switch off” the device when not in use or when not needed.
Therefore it is desirable to provide a self-contained, freestanding device that can be applied to any eye-shielding device, such as a helmet visor, to provide a tinting or light-absorption function. It is also desirable that the change in tint of the viewing area occur more rapidly in response to light (such as sun-glare) or darker conditions than with conventional tint-adjusting devices. Moreover, in some instances, it is desirable that such a device be removable, so that the end user can remove it if he/she does not require its use. It is also desirable to provide a tinting or light-absorbing device with a mechanism whereby the user can exert control over the timing, the degree of the tinting or shading (darkness) and/or the color of the device. In other instances, however, it is desirable that the device react “automatically” to changes in light, with or without user input. Another desirable attribute is a device equipped with a master switch for tuning off the device when not is use, either to save battery life, or to stop the device from functioning if the user so desires.